"This is consistent with what we've been hearing from people," said Steve Anderson, executive vice president of Schwab retirement plan services. "Trying to figure out how to take control of the plans can be overwhelming, especially for someone who doesn't have the time or knowledge."

The nationwide survey of 1,000 401(k) participants, released this month, said 52 percent of those polled find explanations of their investment plans more confusing than their company health-care benefits. And 57 percent said they wished there were an easier way to determine how to choose the right 401(k) investments.

More pressure on workers

401(k) plans (known as defined contribution plans) have been around since 1978. But they have gradually replaced the traditional pension plan and are now the main retirement vehicle for many workers in the private sector, though there is no obligation to have one.

The traditional pension plan (called the defined benefit plan) has both workers and employers making financial contributions, with employees getting a guaranteed source of retirement income.

Managing the defined benefit plan is left to the company, usually through an annuity plan, which invests the money for better returns. In theory, the worker does not have to choose investments.

But the 401(k), which takes contributions from workers and sometimes matching funds from employers, puts pressure on workers to make correct investment choices, as the company offers investment vehicles but does not manage them.

And there is no guaranteed money at retirement with a 401(k).

"A big part of this for people is knowing how much risk to take with their money," said Pace University's Gottesman. "And they get mixed messages about the markets from the media. Some person says buy this stock or fund; another one says sell it. People don't know what to do."

Having right investment choices

To help sort through the maze of 401(k) options—which can include actively managed mutual funds with higher management fees or low-fee index funds—many companies offer aid, especially in the form of education.

"It can get confusing, so we do our best to give workers the knowledge on how to invest," said Parker Pieri, director of finance for the Dwyer Group, a Dallas-based holding company for franchise firms with 450 workers.

"We offer various portfolio models so our workers can get some idea of where they should put their money," he said. "They can see which types of funds to choose if, say, they want to take more risk, or if they want to be more conservative with investing.

"We also have a financial adviser, who is paid out of the general 401(k) funds, available to talk with our workers," Pieri said.

Giving workers the right amount of investment choice is a key to making them happy, said Jeff Wesley, CFO of the Michigan-based moving service firm Two Men and a Truck, which has about 100 employees.

"We are constantly working on making sure there are enough types of funds to invest in as well as looking at what's next for coming 401(k) options, " he said. "And we're seeing the total asset participation up some 30 percent."

"It"s been hard on employees to figure out what to do in the last few years with the market's ups and downs," Wesley added. "It's a taking a lot of work on their part. We're trying to educate them as best we can."

But help from a worker's firm comes with caveats, according to Gottesman.

"You hope the financial advisors know what they're doing," he said. "But if they just put your information into a computer and come out with a plan, it might not be the best one for you.

"They could put you in the managed funds, which have higher fees and thus lower returns for investors," said Gottesman. "Workers, even if they get advice, have to be careful."

'No simple way around this'

According to the Schwab survey, just 5 percent of participants expect to rely on government programs such as Social Security for financial support when they stop working; 89 percent said they aim to come up with the funds for retirement themselves. That's evident in the growth of 401(k)s.